Hello MisionThi!
I've begun developing a resource pack with custom item textures, and found that your mod to be immensely useful while developing.
I do have one suggestion for the mod, and that is the ability to copy the NBT-data of an item to your clipboard.
My process for creating NBT-reliant textures right now is to copy the NBT by hand character by character.
-PolyBit

Thank you for the suggestion, I can look into it when I got some more time on my hands again! :D